Association of One-Step Nucleic Acid AmplificationDetected Micrometastases with Tumour Biology andAdjuvant Chemotherapy

One-step nucleic acid amplification (OSNA) is an intraoperative technique with a high sensitivity and specificity for sentinel nodeassessment. The aim of this study was to assess the impact of OSNA on micrometastases detection rates and use of adjuvantchemotherapy. A retrospective review of patients with sentinel node micrometastases over a five-year period was carried out and acomparison of micrometastases detection using OSNA and H&E techniques was made. Out of 1285 patients who underwent sentinelnode (SLN) biopsy, 76 patients had micrometastases. Using H&E staining, 36 patients were detected with SLN micrometastases(9/year) in contrast to 40 patients in the OSNA year (40/year) (𝑝<0.0001), demonstrating a fourfold increase with the use ofOSNA. In the OSNA group, there was also a proportional increase in Grade III, triple-negative, ER-negative, and HER-2-positivetumours being diagnosed with micrometastases. Also on interactive PREDICT tool, the number of patients with a predicted 10-yearsurvival benefit of more than 3% with adjuvant chemotherapy increased from 52 to 70 percent. OSNA has resulted in an increaseddetection rate of micrometastases especially in patients with aggressive tumour biology. This increased the number of patients whohad a predicted survival benefit from adjuvant chemotherapy.